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Nathan Goodyear

Low free testosterone is associated wit... [Geriatr Gerontol Int. 2014] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...24629182

low Testosterone T free muscle women hormone hormones

shared by Nathan Goodyear on 24 Mar 14 - No Cached
  • Nathan Goodyear on 24 Mar 14
     
    Low free Testosterone associated muscle loss in Japanese women.  This points to other studies that low T can cause problems in women--in this case muscle loss.  Like many things, Testosterone in women is likely a "U" shaped curve of function: low and high are bad with physiologic therapy good.
Nathan Goodyear

Weekly Versus Monthly Testosterone Administration on Fast and Slow ... - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...25387260

Testosterone muscle sarcopenia low T low Testosterone low T men male hormones

shared by Nathan Goodyear on 24 Nov 14 - No Cached
  • Nathan Goodyear on 24 Nov 14
     
    Weekly Testosterone injections increase type 1 slow muscle fibers more than type II fast twitch muscle fibers compared to monthly injections.  The study looked at older men with sarcopenia and low T.
Nathan Goodyear

Muscle satellite cells. - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...12757751

muscle muscle satellite cells

shared by Nathan Goodyear on 06 Mar 15 - No Cached
  • Nathan Goodyear on 06 Mar 15
     
    muscle satellite cells defined
Nathan Goodyear

Hormonal and lifestyle determinants of appendicular skeletal muscle mass in men: the MINOS study - 0 views

ajcn.nutrition.org/...496.long

sarcopenia muscle free Testosterone muscle mass low T low Testosterone vitamin D physical activity smoking

shared by Nathan Goodyear on 05 Mar 15 - No Cached
  • Nathan Goodyear on 05 Mar 15
     
    muscle loss, sarcopenia is a significant marker of poor health in men.  This study of 845 men age 45-85 finds that low Testosterone, low vitamin D, low physical activity, smoking, and thin body build are associated with sarcopenia in men.
Nathan Goodyear

Testosterone administration to elderly men increases skeletal muscle strength and protein synthesis | Endocrinology and Metabolism - 0 views

ajpendo.physiology.org/...E820.short

Testosterone men male hormone hormones muscle muscle mass protein strength metabolism

shared by Nathan Goodyear on 06 Mar 15 - No Cached
  • Nathan Goodyear on 06 Mar 15
     
    small study finds that Testosterone therapy in elderly men increased protein synthesis, muscle mass, and increase in strength.
Nathan Goodyear

Low free testosterone is associated with loss of appendicular muscle mass in Japanese community-dwelling women - Yuki - 2014 - Geriatrics & Gerontology International - Wiley Online Library - 0 views

onlinelibrary.wiley.com/...abstract

free Testosterone Testosterone women female hormone hormones muscle mass muscle loss

shared by Nathan Goodyear on 13 Aug 14 - No Cached
  • Nathan Goodyear on 13 Aug 14
     
    low Free testosterone found to be associated with muscle mass loss in women when compared to high free Testosterone levels.
Nathan Goodyear

Relationship between low free testosterone levels and loss of muscle mass. - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...23660939

free Testosterone total Testosterone muscle Testosterone sarcopenia muscle loss men male hormone hormones

shared by Nathan Goodyear on 05 Apr 15 - No Cached
  • Nathan Goodyear on 05 Apr 15
     
    low free Testosterone associated with muscle loss in men compared to no association with total Testosterone in Japanese men.
Nathan Goodyear

Effects of Age and Sedentary Lifestyle on Skeletal Muscle NF-κB Signaling in Men - 0 views

www.ncbi.nlm.nih.gov/...PMC2904591

aging muscle muscle mass NF-kappaB sedentary lifestyle

shared by Nathan Goodyear on 14 Apr 15 - No Cached
  • Nathan Goodyear on 14 Apr 15
     
    Aging and sedentary lifestyle associated with muscle loss through NF-KappaB activation.
Nathan Goodyear

Nature vs. nurture: can exercise really alter fiber type composition in human skeletal muscle? | Journal of Applied Physiology - 0 views

jap.physiology.org/...1591

muscle muscle fiber physiology

shared by Nathan Goodyear on 20 Mar 15 - No Cached
  • Nathan Goodyear on 20 Mar 15
     
    Muscle fiber types exist on a continuum.
Nathan Goodyear

Testosterone physiology in resistance exercise an... [Sports Med. 2010] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...21058750

resistance exercise physiology testosterone men male hormone hormones

shared by Nathan Goodyear on 29 Jul 14 - No Cached
  • testosterone stimulates protein synthesis
  • promotion of muscle hypertrophy by testosterone
  • intracellular androgen receptor (AR)
  • ...8 more annotations...
  • In general, testosterone concentration is elevated directly following heavy resistance exercise in men
  • Findings on the testosterone response in women are equivocal with both increases and no changes observed in response to a bout of heavy resistance exercise
  • Age also significantly affects circulating testosterone concentrations.
  • Aging beyond 35-40 years is associated with a 1-3% decline per year in circulating testosterone concentration in men
  • aging results in a reduced acute testosterone response to resistance exercise in men.
  • In women, circulating testosterone concentration also gradually declines until menopause, after which a drastic reduction is found.
  • acute increases in testosterone can be induced by resistance exercise
  • testosterone is an important modulator of muscle mass in both men and women
  • Nathan Goodyear on 29 Jul 14
     
    Resistance training to increase endogenous Testosterone production: more specific, the exercise must be high rep or as the authors call it--high volume.  To do this, the weight needs to be light.
Nathan Goodyear

The Single Nucleotide Polymorphism Gly482Ser in the PGC-1α Gene Impairs Exercise-Induced Slow-Twitch Muscle Fibre Transformation in Humans - 0 views

journals.plos.org/...article

epigenetics exercise training muscle SNPs PGC-1alpha

shared by Nathan Goodyear on 30 Nov 17 - No Cached
  • Oxidative slow-twitch type I fibres (henceforth briefly called ‘slow fibres’) contain MHC-Iβ. They use oxidative phosphorylation (OXPHOS) to generate ATP and are thus highly fatigue resistant and preferentially activated during endurance exercise. Slow fibres comprise high amounts of mitochondria, myoglobin and lipid droplets, and are well supplied by capillaries
  • there are three types of fast-twitch fibres (types IIA, IID/X, IIB, with the corresponding MHC isoforms IIa, IId/x, IIb) which are all used for rapid high-force generation. Oxidative-glycolytic fast-twitch type IIA fibres have intermediate amounts of mitochondria, lipid droplets and capillaries, and are intermediately resistant to fatigue (as compared to type I and types IIB and IID/X). Glycolytic fast-twitch type IID/X fibres are poor in mitochondria, lipids and capillaries and more susceptible to fatique than type IIA. Glycolytic fast-twitch type IIB fibres have the lowest amounts of mitochondria, lipid droplets and capillaries, but generate the highest contraction velocities
  • Several studies have shown that PGC-1α is upregulated after endurance training
  • ...3 more annotations...
  • upregulation of PGC-1α expression enhances and/or maintains mitochondrial biogenesis, eventually leading to an increased mitochondrial content of the muscle fibres.
  • PGC-1α also plays an important role in the pathogenesis of insulin resistance and T2D
  • carriers of the Gly482Ser SNP have a reduced cardiorespiratory fitness and a higher risk for metabolic syndrome and T2D
  • Nathan Goodyear on 30 Nov 17
     
    Those that carry the risk SNP for Gly482Ser for the PGC-1alpha gene dont' transform type II to type I and thus decrease the effectiveness of aeorbic exercise training, decreased oxidative phosphorylation, decreased lipid oxidation, increased lipid accumulaiton in muscle, and increased risk of IR, obesity, and diabetes.
Nathan Goodyear

Improving the Vitamin D Status of Vitamin D Deficient Adults Is Associated With Improved Mitochondrial Oxidative Function in Skeletal Muscle - 0 views

jcem.endojournals.org/...E509.abstract

vitamin vitamins vitamin D mitochondria skeletal muscle

shared by Nathan Goodyear on 18 Mar 13 - No Cached
  • Nathan Goodyear on 18 Mar 13
     
    Fascinating link between vitamin D and mitochondria function in skeletal muscle.  Vitamin D replacement was found to improve mitochondrial function, improve post exercise discomfort in those with vitamin D deficiency.  Obviously, this provides support for a link between vitamin D and mitochondrial function.  This could provide an important tool in the recovery phase in athletes.
Nathan Goodyear

Testosterone: a vascular hormone in health and disease - 0 views

joe.endocrinology-journals.org/...R47.full

testosterone hormone health disease hormones men male cardiovascular disease CVD

shared by Nathan Goodyear on 13 May 13 - No Cached
  • Testosterone has beneficial effects on several cardiovascular risk factors, which include cholesterol, endothelial dysfunction and inflammation
  • In clinical studies, acute and chronic testosterone administration increases coronary artery diameter and flow, improves cardiac ischaemia and symptoms in men with chronic stable angina and reduces peripheral vascular resistance in chronic heart failure.
  • testosterone is an L-calcium channel blocker and induces potassium channel activation in vascular smooth muscle cells
  • ...54 more annotations...
  • Animal studies have consistently demonstrated that testosterone is atheroprotective, whereas testosterone deficiency promotes the early stages of atherogenesis
  • there is no compelling evidence that testosterone replacement to levels within the normal healthy range contributes adversely to the pathogenesis of CVD (Carson & Rosano 2011) or prostate cancer (Morgentaler & Schulman 2009)
  • bidirectional effect between decreased testosterone concentrations and disease pathology exists as concomitant cardiovascular risk factors (including inflammation, obesity and insulin resistance) are known to reduce testosterone levels and that testosterone confers beneficial effects on these cardiovascular risk factors
  • Achieving a normal physiological testosterone concentration through the administration of testosterone replacement therapy (TRT) has been shown to improve risk factors for atherosclerosis including reducing central adiposity and insulin resistance and improving lipid profiles (in particular, lowering cholesterol), clotting and inflammatory profiles and vascular function
  • It is well known that impaired erectile function and CVD are closely related in that ED can be the first clinical manifestation of atherosclerosis often preceding a cardiovascular event by 3–5 years
  • no decrease in the response (i.e. no tachyphylaxis) of testosterone and that patient benefit persists in the long term.
  • free testosterone levels within the physiological range, has been shown to result in a marked increase in both flow- and nitroglycerin-mediated brachial artery vasodilation in men with CAD
  • Clinical studies, however, have revealed either small reductions of 2–3 mm in diastolic pressure or no significant effects when testosterone is replaced within normal physiological limits in humans
  • Endothelium-independent mechanisms of testosterone are considered to occur primarily via the inhibition of voltage-operated Ca2+ channels (VOCCs) and/or activation of K+ channels (KCs) on smooth muscle cells (SMCs)
  • Testosterone shares the same molecular binding site as nifedipine
  • Testosterone increases the expression of endothelial nitric oxide synthase (eNOS) and enhances nitric oxide (NO) production
  • Testosterone also inhibited the Ca2+ influx response to PGF2α
  • one of the major actions of testosterone is on NO and its signalling pathways
  • In addition to direct effects on NOS expression, testosterone may also affect phosphodiesterase type 5 (PDE5 (PDE5A)) gene expression, an enzyme controlling the degradation of cGMP, which acts as a vasodilatory second messenger
  • the significance of the action of testosterone on VSMC apoptosis and proliferation in atherosclerosis is difficult to delineate and may be dependent upon the stage of plaque development
  • Several human studies have shown that carotid IMT (CIMT) and aortic calcification negatively correlate with serum testosterone
  • t long-term testosterone treatment reduced CIMT in men with low testosterone levels and angina
  • neither intracellular nor membrane-associated ARs are required for the rapid vasodilator effect
  • acute responses appear to be AR independent, long-term AR-mediated effects on the vasculature have also been described, primarily in the context of vascular tone regulation via the modulation of gene transcription
  • Testosterone and DHT increased the expression of eNOS in HUVECs
  • oestrogens have been shown to activate eNOS and stimulate NO production in an ERα-dependent manner
  • Several studies, however, have demonstrated that the vasodilatory actions of testosterone are not reduced by aromatase inhibition
  • non-aromatisable DHT elicited similar vasodilation to testosterone treatment in arterial smooth muscle
  • increased endothelial NOS (eNOS) expression and phosphorylation were observed in testosterone- and DHT-treated human umbilical vein endothelial cells
  • Androgen deprivation leads to a reduction in neuronal NOS expression associated with a decrease of intracavernosal pressure in penile arteries during erection, an effect that is promptly reversed by androgen replacement therapy
  • Observational evidence suggests that several pro-inflammatory cytokines (including interleukin 1β (IL1β), IL6, tumour necrosis factor α (TNFα), and highly sensitive CRP) and serum testosterone levels are inversely associated in patients with CAD, T2DM and/or hypogonadism
  • patients with the highest IL1β concentrations had lower endogenous testosterone levels
  • TRT has been reported to significantly reduce TNFα and elevate the circulating anti-inflammatory IL10 in hypogonadal men with CVD
  • testosterone treatment to normalise levels in hypogonadal men with the MetS resulted in a significant reduction in the circulating CRP, IL1β and TNFα, with a trend towards lower IL6 compared with placebo
  • parenteral testosterone undecanoate, CRP decreased significantly in hypogonadal elderly men
  • Higher levels of serum adiponectin have been shown to lower cardiovascular risk
  • Research suggests that the expression of VCAM-1, as induced by pro-inflammatory cytokines such as TNFα or interferon γ (IFNγ (IFNG)) in endothelial cells, can be attenuated by treatment with testosterone
  • Testosterone also inhibits the production of pro-inflammatory cytokines such as IL6, IL1β and TNFα in a range of cell types including human endothelial cells
  • decreased inflammatory response to TNFα and lipopolysaccharide (LPS) in human endothelial cells when treated with DHT
  • The key to unravelling the link between testosterone and its role in atherosclerosis may lay in the understanding of testosterone signalling and the cross-talk between receptors and intracellular events that result in pro- and/or anti-inflammatory actions in athero-sensitive cells.
  • testosterone functions through the AR to modulate adhesion molecule expression
  • pre-treatment with DHT reduced the cytokine-stimulated inflammatory response
  • DHT inhibited NFκB activation
  • DHT could inhibit an LPS-induced upregulation of MCP1
  • Both NFκB and AR act at the transcriptional level and have been experimentally found to be antagonistic to each other
  • As the AR and NFκB are mutual antagonists, their interaction and influence on functions can be bidirectional, with inflammatory agents that activate NFκB interfering with normal androgen signalling as well as the AR interrupting NFκB inflammatory transcription
  • prolonged exposure of vascular cells to the inflammatory activation of NFκB associated with atherosclerosis may reduce or alter any potentially protective effects of testosterone
  • DHT and IFNγ also modulate each other's signalling through interaction at the transcriptional level, suggesting that androgens down-regulate IFN-induced genes
  • (Simoncini et al. 2000a,b). Norata et al. (2010) suggest that part of the testosterone-mediated atheroprotective effects could depend on ER activation mediated by the testosterone/DHT 3β-derivative, 3β-Adiol
  • TNFα-induced induction of ICAM-1, VCAM-1 and E-selectin as well as MCP1 and IL6 was significantly reduced by a pre-incubation with 3β-Adiol in HUVECs
  • 3β-Adiol also reduced LPS-induced gene expression of IL6, TNFα, cyclooxygenase 2 (COX2 (PTGS2)), CD40, CX3CR1, plasminogen activator inhibitor-1, MMP9, resistin, pentraxin-3 and MCP1 in the monocytic cell line U937 (Norata et al. 2010)
  • This study suggests that testosterone metabolites, other than those generated through aromatisation, could exert anti-inflammatory effects that are mediated by ER activation.
  • The authors suggest that DHT differentially effects COX2 levels under physiological and pathophysiological conditions in human coronary artery smooth muscle cells and via AR-dependent and -independent mechanisms influenced by the physiological state of the cell
  • There are, however, a number of systematic meta-analyses of clinical trials of TRT that have not demonstrated an increased risk of adverse cardiovascular events or mortality
  • The TOM trial, which was designed to investigate the effect of TRT on frailty in elderly men, was terminated prematurely as a result of an increased incidence of cardiovascular-related events after 6 months in the treatment arm
  • trials of TRT in men with either chronic stable angina or chronic cardiac failure have also found no increase in either cardiovascular events or mortality in studies up to 12 months
  • Evidence may therefore suggest that low testosterone levels and testosterone levels above the normal range have an adverse effect on CVD, whereas testosterone levels titrated to within the mid- to upper-normal range have at least a neutral effect or, taking into account the knowledge of the beneficial effects of testosterone on a series of cardiovascular risk factors, there may possibly be a cardioprotective action
  • The effect of testosterone on human vascular function is a complex issue and may be dependent upon the underlying androgen and/or disease status.
  • the majority of studies suggest that testosterone may display both acute and chronic vasodilatory effects upon various vascular beds at both physiological and supraphysiological concentrations and via endothelium-dependent and -independent mechanisms
  • Nathan Goodyear on 13 May 13
     
    Good deep look into the testosterone and CVD link.
Nathan Goodyear

JAMA Network | JAMA | Association of All-Cause Mortality With Overweight and Obesity Using Standard Body Mass Index CategoriesA Systematic Review and Meta-analysisAll-Cause Mortality Using BMI Categories - 0 views

jama.jamanetwork.com/article.aspx

obese obesity overweight mortality

shared by Nathan Goodyear on 02 Jan 13 - No Cached
  • Nathan Goodyear on 02 Jan 13
     
    Don't get to excited about this article.  It is just a meta-analysis.  Second, they looked at BMI and BMI is a notoriously bad estimater of muscle mass versus fat content.  I am the perfect example, my BMI has me as obese, yet my measured fat % is 16%.   My read on this, is most of the individuals that are "overweight" are actually at a health weight with a higher muscle mass percentage not picked up with the BMI measurement.
Nathan Goodyear

Nutrition and muscle protein synthesis: a descriptive review - 0 views

www.ncbi.nlm.nih.gov/...PMC2732256

protein muscle nutrition

shared by Nathan Goodyear on 01 Feb 13 - No Cached
  • Nathan Goodyear on 01 Feb 13
     
    review of literature on protein intake to maximize muscle growth
Nathan Goodyear

Testosterone Improves the Regeneration of Old and Young Mouse Skeletal Muscle - 0 views

biomedgerontology.oxfordjournals.org/...17.abstract

testosterone muscle male hormone hormones

shared by Nathan Goodyear on 25 Jan 13 - No Cached
  • Nathan Goodyear on 25 Jan 13
     
    Yes, this is a mouse study. But, testosterone shown to improve muscle growth.  This is only in "aged" mice.
Nathan Goodyear

ScienceDirect.com - Cell Metabolism - Estrogen Receptors and the Metabolic Network - 0 views

www.sciencedirect.com/...S1550413111003123

ER-alpha ER-beta estrogen receptor receptors metabolic syndrome MetS hormone hormones

shared by Nathan Goodyear on 11 Oct 12 - No Cached
  • The pro-opiomelanocortin (POMC) neurons have an anorexigenic action and, when activated, reduce food intake through the release of two peptides, α-melanocyte-stimulating hormone (α-MSH) and cocaine-and-amphetamine-regulated transcripts (CART). The neuropeptide Y (NPY) neurons, on the other hand, release NPY hormone and agouti gene-related protein (AgRP), which prevent the binding of α-MSH to MC3R and MC4R, increasing food intake
  • This suggests that the central anorexic effects of E2 may occur via ERβ
  • The main hypothalamic areas involved in food intake and satiety are the arcuate nucleus (ARC), the lateral hypothalamus (LH), the paraventricular nucleus (PVN), the ventromedial hypothalamus (VMH), and the dorsomedial hypothalamus (DMH)
  • ...22 more annotations...
  • Leptin is a potent anorexigenic and catabolic hormone secreted by adipose cells that reduces food intake and increases energy expenditure
  • E2 not only modulates leptin receptor mRNA in the ARC and VMH, but also increases hypothalamic sensitivity to leptin, altering peripheral fat distribution
  • ghrelin. It acts on growth hormone secretagogue receptors (GHSR1a) located in the ARC and is a potent stimulator of food intake
  • It thus appears that of the two ERs, ERα plays a predominant role in the CNS regulation of lipid and carbohydrate homeostasis.
  • Both ERs have been identified in the ARC
  • Stimulation of MCH neurons increases food intake and fat accumulation while its inhibition leads to decreased food intake and reduced fat accumulation.
  • Both ERs have been identified in the LH
  • both ERs have been identified in this nucleus
  • The PVN is the region of the hypothalamus with the highest expression of ERβ and is reported to be weakly ERα positive
  • The VMH is ERα regulated
  • Skeletal muscle is responsible for 75% of the insulin-induced glucose uptake in the body
  • GLUT4 is highly expressed in muscle and represents a rate-limiting step in the insulin-induced glucose uptake
  • data suggest that in the physiological range, E2 is beneficial for insulin sensitivity, whereas hypo- or hyperestrogenism is related to insulin resistance
  • In aging female rats, E2 treatment improves glucose homeostasis mainly through its ability to increase muscle GLUT4 content on the cell membrane
  • It is evident that ERα and ERβ have distinct actions and that much more research is needed to clearly identify the function of each receptor in muscle.
  • E2 prevents accumulation of visceral fat, increases central sensitivity to leptin, increases the expression of insulin receptors in adipocytes, and decreases the lipogenic activity of lipoprotein lipase in adipose tissue
  • In rats, ovariectomy increases body weight, intra-abdominal fat, fasting glucose and insulin levels, and insulin resistance followed by decreased phosphorylation of AMPK and its substrate acetyl-CoA carboxylase in adipose tissue
  • decreased adiponectin, PPARγ coactivator-1α (PGC-1α), and uncoupling protein 2 (UCP2) and increased resistin
  • Men with aromatase deficiency have truncal obesity, elevated blood lipids, and severe insulin resistance
  • Although not all studies are in agreement, polymorphisms of ERα in humans have been associated with risk factors for CVDs
  • Human subcutaneous and visceral adipose tissues express both ERα and ERβ, whereas only ERα mRNA has been identified in brown adipose tissue
  • suggesting that ERα is the main regulator of GLUT4 expression in adipose tissue
  • Nathan Goodyear on 11 Oct 12
     
    very nice article that looks at the balance of ER-alpha/ER-beta and their role in metabolic syndrome.  This article discusses the balance of  these receptors are tissue dependent in their effect.  I like their conclusion: "...but these mechanisms will never be completely understood if they are not considered in the context of a whole system.
Nathan Goodyear

PLOS ONE: Overexpression of the Mitochondrial T3 Receptor Induces Skeletal Muscle Atrophy during Aging - 0 views

www.plosone.org/...journal.pone.0005631

muscle aging T3 thyroid hormone hormones

shared by Nathan Goodyear on 29 Jun 13 - No Cached
  • Nathan Goodyear on 29 Jun 13
     
    Overexpression of T3 receptors can contribute to muscle loss with aging.  
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